I liked the bonus missions in the deluxe edition. Hopefully they have some additions planned for the PC version. I read somewhere that something is planned but exclusively for the PS3 console version... http://www.psxextreme.com/ps3-news/12353.html
the high tides co op is exclusive to ps 3, hopefully for just awhile
single player looks almost complete while co-op missions have a lot more potential for fun activities, they could do animal hunting co op dlc, fishing dlc, scuba diving dlc, island sports dlc like air gliding/sky diving or dirt bike rally, the possibilities are endless
My vote would be for a new SP campaign centered around the Vaas character. Maybe a back story about his falling out with his tribe and sister. How he's lured from the good path to the dark and twisted place we've seen him in FC3. You play as Vaas, starts off as a good guy but goes very bad. I saw this mentioned in another thread and think a story like that could be pretty good.
Now that I have finished the Missions and cleaned up the World, I too want more. What a great game! Superb acting, Hate Jason's voice (hardly a killer), now starting the tougher levels. Loved FC2, worked it to death, FC3 came by just in time, and hoping FC4 will do the same in the future. Ubisoft should be proud.